Make the deserialization support correctly optional documents

meilidb-core/src/database.rs

@@ -226,7 +226,10 @@ impl Database {
 #[cfg(test)]
 mod tests {
     use super::*;
+
     use crate::update::{ProcessedUpdateResult, UpdateStatus};
+    use crate::DocumentId;
+    use serde::de::IgnoredAny;
     use std::sync::mpsc;
 
     #[test]
@@ -529,4 +532,85 @@ mod tests {
         let result = index.update_status(&reader, update_id).unwrap();
         assert_matches!(result, UpdateStatus::Processed(status) if status.result.is_err());
     }
+
+    #[test]
+    fn deserialize_documents() {
+        let dir = tempfile::tempdir().unwrap();
+
+        let database = Database::open_or_create(dir.path()).unwrap();
+        let env = &database.env;
+
+        let (sender, receiver) = mpsc::sync_channel(100);
+        let update_fn = move |update: ProcessedUpdateResult| sender.send(update.update_id).unwrap();
+        let index = database.create_index("test").unwrap();
+
+        let done = database.set_update_callback("test", Box::new(update_fn));
+        assert!(done, "could not set the index update function");
+
+        let schema = {
+            let data = r#"
+                identifier = "id"
+
+                [attributes."name"]
+                displayed = true
+                indexed = true
+
+                [attributes."description"]
+                displayed = true
+                indexed = true
+            "#;
+            toml::from_str(data).unwrap()
+        };
+
+        let mut writer = env.write_txn().unwrap();
+        let _update_id = index.schema_update(&mut writer, schema).unwrap();
+
+        // don't forget to commit...
+        writer.commit().unwrap();
+
+        let mut additions = index.documents_addition();
+
+        // DocumentId(7900334843754999545)
+        let doc1 = serde_json::json!({
+            "id": 123,
+            "name": "Marvin",
+            "description": "My name is Marvin",
+        });
+
+        // DocumentId(8367468610878465872)
+        let doc2 = serde_json::json!({
+            "id": 234,
+            "name": "Kevin",
+            "description": "My name is Kevin",
+        });
+
+        additions.update_document(doc1);
+        additions.update_document(doc2);
+
+        let mut writer = env.write_txn().unwrap();
+        let update_id = additions.finalize(&mut writer).unwrap();
+
+        // don't forget to commit...
+        writer.commit().unwrap();
+
+        // block until the transaction is processed
+        let _ = receiver.into_iter().find(|id| *id == update_id);
+
+        let reader = env.read_txn().unwrap();
+        let result = index.update_status(&reader, update_id).unwrap();
+        assert_matches!(result, UpdateStatus::Processed(status) if status.result.is_ok());
+
+        let document: Option<IgnoredAny> = index.document(&reader, None, DocumentId(25)).unwrap();
+        assert!(document.is_none());
+
+        let document: Option<IgnoredAny> = index
+            .document(&reader, None, DocumentId(7900334843754999545))
+            .unwrap();
+        assert!(document.is_some());
+
+        let document: Option<IgnoredAny> = index
+            .document(&reader, None, DocumentId(8367468610878465872))
+            .unwrap();
+        assert!(document.is_some());
+    }
 }

meilidb-core/src/serde/deserializer.rs

@@ -63,13 +63,14 @@ impl<'de, 'a, 'b> de::Deserializer<'de> for &'b mut Deserializer<'a> {
     where
         V: de::Visitor<'de>,
     {
-        self.deserialize_map(visitor)
+        self.deserialize_option(visitor)
     }
 
-    forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
-        bytes byte_buf option unit unit_struct newtype_struct seq tuple
-        tuple_struct struct enum identifier ignored_any
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: de::Visitor<'de>,
+    {
+        self.deserialize_map(visitor)
     }
 
     fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -104,16 +105,29 @@ impl<'de, 'a, 'b> de::Deserializer<'de> for &'b mut Deserializer<'a> {
                 }
             });
 
-        let map_deserializer = de::value::MapDeserializer::new(iter);
-        let result = visitor
-            .visit_map(map_deserializer)
-            .map_err(DeserializerError::from);
+        let mut iter = iter.peekable();
+
+        let result = match iter.peek() {
+            Some(_) => {
+                let map_deserializer = de::value::MapDeserializer::new(iter);
+                visitor
+                    .visit_some(map_deserializer)
+                    .map_err(DeserializerError::from)
+            }
+            None => visitor.visit_none(),
+        };
 
         match error.take() {
             Some(error) => Err(error.into()),
             None => result,
         }
     }
+
+    forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf unit unit_struct newtype_struct seq tuple
+        tuple_struct struct enum identifier ignored_any
+    }
 }
 
 struct Value(SerdeJsonDeserializer<SerdeJsonIoRead<Cursor<Vec<u8>>>>);

meilidb-core/src/store/mod.rs

@@ -22,7 +22,7 @@ use std::collections::HashSet;
 
 use heed::Result as ZResult;
 use meilidb_schema::{Schema, SchemaAttr};
-use serde::de;
+use serde::de::{self, Deserialize};
 use zerocopy::{AsBytes, FromBytes};
 
 use crate::criterion::Criteria;
@@ -120,9 +120,7 @@ impl Index {
             attributes: attributes.as_ref(),
         };
 
-        // TODO: currently we return an error if all document fields are missing,
-        //       returning None would have been better
-        Ok(T::deserialize(&mut deserializer).map(Some)?)
+        Ok(Option::<T>::deserialize(&mut deserializer)?)
     }
 
     pub fn document_attribute<T: de::DeserializeOwned>(